Originally Posted by John long
There are several ways. Some of spot welds might be able to be drilled out from the top. Some of them can be ground out with a cut-off disk on a die grinder. It is time consuming but you can get them off without destroying the cab. If you do drill them out from the top, plug weld them when you put the new mount in. It makes a very neat installation.
As John said "time consuming" this is of up most importance, to accept that it takes some time. And that is the key, clean up the area good exposing every weld so you can remove it. You remove the weld just like "unbolting" it. Don't loose sight of that, simply remove each weld, one at a time. Some you use a die grinder with a cut off disc, others you drill out, some from the top, some from the bottom, sometimes you have no choice, it's where you have access.
Here is a "Basics of Basics" on the subject of removing spot welded on parts. "Basics of Basics" Spot welds, removing welded on panels.
Just take your time, you wouldn't remove a bolted on fender with an air chisel or a torch right? Why remove a spot welded on part with one? Simply "un-bolt" it, it's that simple.